This looks to be a Pieris rapae. It didn’t move to a better location for a better ID photo so this is all we have. I have seen them flittering on the wild mustard that is blooming now. No photos though as it has been very windy when they’ve been feeding. This one might be laying eggs.

The Monarchs have been around for a week or so, usually feeding on Orange Hawkweeds. The Common Milkweeds won’t be blooming for a week or so. I suspect that this Monarch is in the milkweeds to lay eggs for the first generation of summer Monarchs.